ToastService.cs

using Windows.Data.Xml.Dom;
using Windows.UI.Notifications;

namespace BatteryDown;

internal static class ToastService
{
    private const string PromptTag = "power-prompt";
    private const string PromptGroup = "battery";

    public static async Task ShowPromptAsync(AppConfig config, bool isPreview = false)
    {
        if (!isPreview && LockScreenPolicy.HandleIfLocked(config))
        {
            return;
        }

        RegistrationService.EnsureRegistered();
        ClearPrompt();

        var countdownSeconds = config.ShutdownDelaySeconds;
        var planToken = isPreview ? null : ShutdownPlanService.Schedule(countdownSeconds);
        var continueAction = isPreview ? "preview-continue" : "continue";
        var shutdownAction = isPreview ? "preview-shutdown" : "shutdown";

        try
        {
            var xml = new XmlDocument();
            xml.LoadXml($$"""
                <toast launch="{{RegistrationService.ProtocolName}}://open" scenario="reminder" duration="long">
                  <visual>
                    <binding template="ToastGeneric">
                      <text>{{(isPreview ? "Battery Down 通知预览" : "是否需要继续使用电脑？")}}</text>
                      <text>{countdownText}</text>
                    </binding>
                  </visual>
                  <actions>
                    <action content="继续使用" arguments="{{RegistrationService.ProtocolName}}://{{continueAction}}" activationType="protocol" />
                    <action content="立即关机" arguments="{{RegistrationService.ProtocolName}}://{{shutdownAction}}" activationType="protocol" />
                  </actions>
                </toast>
                """);

            var data = new NotificationData();
            data.Values["countdownText"] = CountdownText(countdownSeconds, isPreview);
            data.SequenceNumber = 0;

            var toast = new ToastNotification(xml)
            {
                Tag = PromptTag,
                Group = PromptGroup,
                ExpirationTime = DateTimeOffset.Now.AddSeconds(countdownSeconds + 30),
                SuppressPopup = false,
                Data = data,
            };

            var notifier = ToastNotificationManager.CreateToastNotifier(RegistrationService.AppUserModelId);
            notifier.Show(toast);

            for (var remaining = countdownSeconds - 1; remaining >= 0; remaining--)
            {
                await Task.Delay(TimeSpan.FromSeconds(1));

                if (!isPreview &&
                    (planToken is null || !ShutdownPlanService.IsActive(planToken)))
                {
                    return;
                }

                if (!isPreview && !PowerStatus.IsOnBattery)
                {
                    ShutdownPlanService.Cancel();
                    ClearPrompt();
                    return;
                }

                if (!isPreview && LockScreenPolicy.HandleIfLocked(config))
                {
                    return;
                }

                if (remaining == 0 && isPreview)
                {
                    ClearPrompt();
                    return;
                }

                data.Values["countdownText"] = remaining == 0
                    ? "倒计时结束，正在关机..."
                    : CountdownText(remaining, isPreview);
                data.SequenceNumber++;
                _ = notifier.Update(data, PromptTag, PromptGroup);
            }
        }
        catch
        {
            if (!isPreview)
            {
                ShutdownPlanService.Cancel();
            }

            throw;
        }
    }

    private static string CountdownText(int seconds, bool isPreview)
    {
        var prefix = isPreview ? "预览倒计时" : "若无操作，电脑将在";
        var suffix = isPreview ? "秒后关闭此预览。" : "秒后自动关机。";
        return $"{prefix} {seconds} {suffix}";
    }

    public static void ClearPrompt()
    {
        try
        {
            ToastNotificationManager.History.Remove(
                PromptTag,
                PromptGroup,
                RegistrationService.AppUserModelId);
        }
        catch
        {
            // Cancellation is best effort when notifications are disabled or not registered yet.
        }
    }
}